This invention relates to an improved construction of coke oven door to be fitted to the openings at both sides of the battery, i.e. the pusher side and the coke side. Conventional constructions of coke oven doors are apt to gradually bend outwards due to temperature difference between the inner surface which is directly subjected to high coke oven temperatures and the outer surface which is exposed to the atmosphere or ambient air. When this results, oven gas leakage occurs between the clearances formed at both the upper and lower portions of the door. A door knife edge or seal has heretofore been fitted to the peripheral portion of the door to prevent such leakage. However, since the knife edge bends together with the door, its tapping-out adjustment or reinstallation is required. With all such constructions, complete prevention of the gas leakage can not be achieved.